added support to save values as integers in mongo collections

I added support to save values as integers into a mongo collection using the Mongo **MongoInt32** and **MongoInt64** classes.

When you explicitly want to save a value as an integer to a collection you can do so.
for example if you do:
```php
$object->value = (int) Input::get('value');
```
The value will be stored as an integer instead of as a String.